Excavator Implement Angle Determination Using A Laser Distance Meter

ABSTRACT

An excavator calibration framework comprises an excavator, a laser distance meter (LDM), and a plurality of laser reflectors. The excavator comprises a chassis, linkage assembly (LA), implement, and control architecture. The LA comprises a boom, stick, the implement, and a four-bar linkage including nodes, with a laser reflector at each node. The control architecture comprises a controller programmed to execute an iterative process at n linkage assembly positions to determine a position of an nth calibration node of the plurality of nodes of the four-bar linkage to determine triangular angles and side lengths of an external triangle formed between the nth calibration node and two other nodes having identified positions. The iterative process is repeated n times until triangular angles and side lengths of three external triangles are determined that form an internal triangle. Angles of the internal triangle are determined to generate an implement angle.

BACKGROUND

The present disclosure relates to excavators which, for the purposes ofdefining and describing the scope of the present application, comprisean excavator boom and an excavator stick subject to swing and curl, andan excavating implement that is subject to swing and curl control withthe aid of the excavator boom and excavator stick, or other similarcomponents for executing swing and curl movement. For example, and notby way of limitation, many types of excavators comprise a hydraulicallyor pneumatically or electrically controlled excavating implement thatcan be manipulated by controlling the swing and curl functions of anexcavating linkage assembly of the excavator. Excavator technology is,for example, well represented by the disclosures of U.S. Pat. No.8,689,471, which is assigned to Caterpillar Trimble Control TechnologiesLLC and discloses methodology for sensor-based automatic control of anexcavator, US 2008/0047170, which is assigned to Caterpillar TrimbleControl Technologies LLC and discloses an excavator 3D laser system andradio positioning guidance system configured to guide a cutting edge ofan excavator bucket with high vertical accuracy, and US 2008/0000111,which is assigned to Caterpillar Trimble Control Technologies LLC anddiscloses methodology for an excavator control system to determine anorientation of an excavator sitting on a sloped site.

BRIEF SUMMARY

According to the subject matter of the present disclosure, an excavatorcalibration framework comprises an excavator, a laser distance meter(LDM), and a plurality of laser reflectors. The excavator comprises amachine chassis, an excavating linkage assembly, an excavatingimplement, and control architecture. The excavating linkage assemblycomprises an excavator boom, an excavator stick, the excavatingimplement, and a four-bar linkage that collectively define a pluralityof linkage assembly positions. The excavator stick comprises a terminalpoint and is mechanically coupled to a terminal pivot point B of theexcavator boom. The four-bar linkage comprises a node D, a node F, anode G, a node H, and linkages disposed therebetween. The node G of thefour-bar linkage is disposed at a position corresponding to the terminalpoint of the excavator stick through which the excavator stick iscoupled to the excavating implement. The LDM is configured to generatean LDM distance signal D_(LDM) indicative of a distance between the LDMand the laser reflector and an angle of inclination signal θ_(INC)indicative of an angle between the LDM and the laser reflector. Theplurality of laser reflectors are disposed at respective positionscorresponding to the nodes D, F, G, and H of the four-bar linkage. Thecontrol architecture comprises one or more linkage assembly actuatorsand an architecture controller programmed to execute an iterativeprocess at n linkage assembly positions. The iterative process comprisespositioning the excavating linkage assembly at a linkage assemblyposition n, setting one of the nodes D, F, G, and H as the nthcalibration node with the excavating linkage assembly at the linkageassembly position n, and determining a height Ĥ and a distance{circumflex over (D)} between the nth calibration node and the LDM basedon the LDM distance signal D_(LDM) and angle of inclination signalθ_(INC). The iterative process further comprises determining a positionof the nth calibration node at least partially based on the height Ĥ andthe distance {circumflex over (D)}, and identifying respective positionsof two other nodes that, together with the nth calibration node, form anexternal triangle. The two other nodes comprise one of nodes D, F, G, H,and a node corresponding to a position of the terminal pivot point B ofthe excavator boom. The iterative process further comprises determiningside lengths for each of the legs of the external triangle formedbetween the nth calibration node and two other nodes, and determiningtriangular angles of the external triangle based on the side lengths ofthe external triangle. The architecture controller is further programmedto repeat the iterative process n times until triangular angles and sidelengths of at least three external triangles are determined. Theexternal triangles form an internal triangle therebetween, the internaltriangle shares two nodes and one side with each of the three externaltriangles and comprises a set of three internal triangle side lengths.The architecture controller is further programmed to determine theangles of the internal triangle at least partially based on the set ofthree internal triangle side length, generate an implement angle of theexcavating implement at least partially based on a summation of a set ofadjacent determined triangular angles, and operate the excavator usingthe implement angle. The set of adjacent determined triangular anglescomprise an angle from the internal triangle and angles from at leasttwo of the external triangles.

In accordance with one embodiment of the present disclosure, anexcavator calibration framework comprises an excavator, a laser distancemeter (LDM), and a plurality of laser reflectors. The excavatorcomprises a machine chassis, an excavating linkage assembly, anexcavating implement, and control architecture. The excavating linkageassembly comprises an excavator boom, an excavator stick, the excavatingimplement, and a four-bar linkage that collectively define a pluralityof linkage assembly positions. The LDM is configured to generate an LDMdistance signal D_(LDM) indicative of a distance between the LDM and thelaser reflector and an angle of inclination signal θ_(INC) indicative ofan angle between the LDM and the laser reflector. The plurality of laserreflectors are disposed at respective positions corresponding to aplurality of nodes of the four-bar linkage. The control architecturecomprises one or more linkage assembly actuators and an architecturecontroller programmed to execute an iterative process at n linkageassembly positions to determine a position of an nth calibration node ofthe plurality of nodes of the four-bar linkage to determine triangularangles and side lengths of an external triangle formed between the nthcalibration node and two other nodes having identified positions. Thearchitecture controller is further programmed to repeat the iterativeprocess n times until triangular angles and side lengths of at leastthree external triangles are determined. The external triangles form aninternal triangle therebetween, the internal triangle shares two nodesand one side with each of the three external triangles and comprises aset of three internal triangle side lengths. The architecture controlleris further programmed to determine the angles of the internal triangleat least partially based on the set of three internal triangle sidelengths, generate an implement angle of the excavating implement atleast partially based on a summation of a set of adjacent determinedtriangular angles, and operate the excavator using the implement angle.The set of adjacent determined triangular angles comprise an angle fromthe internal triangle and angles from at least two of the externaltriangles.

Although the concepts of the present disclosure are described hereinwith primary reference to the excavator illustrated in FIG. 1, it iscontemplated that the concepts will enjoy applicability to any type ofexcavator, regardless of its particular mechanical configuration. Forexample, and not by way of limitation, the concepts may enjoyapplicability to a backhoe loader including a backhoe linkage.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following detailed description of specific embodiments of thepresent disclosure can be best understood when read in conjunction withthe following drawings, where like structure is indicated with likereference numerals and in which:

FIG. 1 is a side view of an excavator incorporating aspects of thepresent disclosure;

FIG. 2 is a perspective view of a dynamic sensor disposed on a linkageof the excavator of FIG. 1 and according to various concepts of thepresent disclosure;

FIG. 3 is a side elevation view of a linkage assembly of an excavatorcalibration framework including a laser distance meter (LDM) of theexcavator of FIG. 1;

FIG. 4 is a side elevation view of a four-bar linkage assembly of theexcavator of FIG. 1, according to various concepts of the presentdisclosure; and

FIG. 5 is a flow chart of a process used to determine an implement angleof an excavating implement of the excavator of FIG. 1.

DETAILED DESCRIPTION

The present disclosure relates to earthmoving machines and, moreparticularly, to earthmoving machines such as excavators includingcomponents subject to control. For example, and not by way oflimitation, many types of excavators typically have a hydraulicallycontrolled earthmoving implement that can be manipulated by a joystickor other means in an operator control station of the machine, and isalso subject to partially or fully automated control. The user of themachine may control the lift, tilt, angle, and pitch of the implement.In addition, one or more of these variables may also be subject topartially or fully automated control based on information sensed orreceived by an adaptive environmental sensor of the machine. In theembodiments described herein, an excavator calibration frameworkutilizes a laser distance meter to determine an implement angle of anexcavating implement of an excavator, as described in greater detailfurther below. Such determined values may be utilized by an excavatorcontrol to operate the excavator.

Referring initially to FIG. 1, excavator calibration framework comprisesan excavator 100, a laser distance meter (LDM) 124, and a plurality oflaser reflectors 130A, 130B, 130C, and 130D. The excavator comprises amachine chassis 102, an excavating linkage assembly 104, an excavatingimplement 114, and control architecture 106. The excavating linkageassembly 104 comprises an excavator boom 108, an excavator stick 110,the excavating implement 114, and a four-bar linkage 112 thatcollectively define a plurality of linkage assembly positions. Theexcavator stick 110 comprises a terminal point and is mechanicallycoupled to a terminal pivot point B of the excavator boom 108. Themachine chassis 102 is mechanically coupled to a terminal pivot point Aof the excavator boom 108. In embodiments, the excavating linkageassembly 104 is configured to swing with, or relative to, the machinechassis 102, and the excavator stick 110 is configured to curl relativeto the excavator boom 108. Further, the excavating implement 114 and theexcavator stick 110 are mechanically coupled to each other through thefour-bar linkage 112.

The four-bar linkage 112 comprises a node D, a node F, a node G, a nodeH, and linkages disposed therebetween. In embodiments, the linkagescomprise an implement linkage GH, a rear side linkage FH, a dogbonelinkage DF, and a front side linkage GD. The implement linkage GH isdisposed between respective positions corresponding to the node G andthe node H. The rear side linkage FH is disposed between respectivepositions corresponding to the node F and the node H. The dogbonelinkage DF is disposed between respective positions corresponding to thenode D and the node F. The front side linkage GD is disposed betweenrespective positions corresponding to the node D and the node G.

The node G of the four-bar linkage 112 is disposed at a positioncorresponding to the terminal point of the excavator stick 110 throughwhich the excavator stick 110 is coupled to the excavating implement114. The LDM 124 is configured to generate an LDM distance signalD_(LDM) indicative of a distance between the LDM and the laser reflector(for example, one of 130A-130D) and an angle of inclination signalθ_(INC) indicative of an angle between the LDM and the laser reflector(for example, one of 130A-130D). The plurality of laser reflectors 130A,130B, 130C, and 130D are disposed at respective positions correspondingto the nodes D, F, G, and H of the four-bar linkage 112. In embodiments,the laser reflector (for example, one of 130A-130D) is on a pole orsecured directly to the corresponding nodes. The LDM 124 may be, forexample, a Bosch GLM 100C LDM as made commercially available by RobertBosch GmbH of Germany. A laser signal from the LDM 124, which is placedon ground 126, may be transmitted in a direction of an arrow 132 to thecalibration node and an aligned laser reflector, and the laser signalmay be reflected back to the LDM 124 in the direction of an arrow 134,as illustrated in FIG. 1.

The control architecture 106 comprises one or more linkage assemblyactuators and an architecture controller programmed to execute aniterative process at n linkage assembly positions. In embodiments, thecontrol architecture 106 comprises a non-transitory computer-readablestorage medium comprising machine readable instructions. The one or morelinkage assembly actuators may facilitate movement of the excavatinglinkage assembly 104. The one or more linkage assembly actuators maycomprise a hydraulic cylinder actuator, a pneumatic cylinder actuator,an electrical actuator, a mechanical actuator, or combinations thereof.

Steps 202-218 of a control scheme 200 of FIG. 5 illustrate the iterativeprocess. In step 202, the iterative process starts with n=1 at a firstlinkage assembly position. In embodiments, for n=1, the 1st calibrationnode is positioned at the node D, for n=2, the 2nd calibration node ispositioned at the node F, and for n=3, the 3rd calibration node ispositioned at the node H.

In step 204, the iterative process comprises positioning the excavatinglinkage assembly 104 at a linkage assembly position n, setting one ofthe nodes D, F, G, and H as the nth calibration node with the excavatinglinkage assembly 104 at the linkage assembly position n. In steps206-208, the iterative process comprises determining a height Ĥ and adistance {circumflex over (D)} between the nth calibration node and theLDM based on the LDM distance signal D_(LDM) and angle of inclinationsignal θ_(INC). In step 210, the iterative process comprises determininga position of the nth calibration node at least partially based on theheight Ĥ and the distance {circumflex over (D)}. In embodiments of theiterative process, determining a position of the nth calibration node atleast partially based on the height Ĥ and the distance {circumflex over(D)} comprises calculating a total height Ĥ and a total distance{circumflex over (D)} between the nth calibration node and the terminalpivot point A of the excavator boom 108. Referring to FIG. 3, thecalculation is based on a summation of the height Ĥ and the distance{circumflex over (D)} between the nth calibration node and the LDM 124and the height H₀ and the distance D₀ between the LDM 124 and theterminal pivot point A. The height Ĥ and the distance {circumflex over(D)} between the nth calibration node and the LDM 124 is determined pera following set of equations:

{circumflex over (D)}=D_(LDM) cos(θ_(INC)), and

Ĥ=D_(LDM) sin(θ_(INC)).   (Equations 1-2)

Further, referring to FIG. 4 and in an embodiment when n=1 and the 1stcalibration node is positioned at the node D, calculating a total height{hacek over (H)} and a total distance Ď between the 1st calibration nodeand the terminal pivot point A of the excavator boom, respectivelycomprising D_(y) and D_(x), based on a summation of the height Ĥ and thedistance {circumflex over (D)} between the 1st calibration node and theLDM and the height H₀ and the distance D₀ between the LDM and theterminal pivot point A comprises use of a following set of questions:

D _(y) =H ₀ +Ĥ _(D), and

D _(x) =D ₀ +{circumflex over (D)} _(D).   (Equations 3-4)

In an embodiment when n=2, the 2nd calibration node is positioned at pinF, such that calculating a total height {hacek over (H)} and a totaldistance Ď between the 2nd calibration node and the terminal pivot pointA of the excavator boom, respectively comprising F_(y) and F_(x), basedon a summation of the height Ĥ and the distance {circumflex over (D)}between the 3rd calibration node and the LDM and the height H₀ and thedistance D₀ between the LDM and the terminal pivot point A comprises useof a following set of equations:

F _(y) =H ₀ +Ĥ _(F), and

F _(x) =D ₀ +{circumflex over (D)} _(F).   (Equations 5-6)

In an embodiment when n=3, the 3rd calibration node is positioned at pinH, such that calculating a total height {hacek over (H)} and a totaldistance Ď between the 3rd calibration node and the terminal pivot pointA of the excavator boom, respectively comprising H_(y) and H_(x), basedon a summation of the height Ĥ and the distance {circumflex over (D)}between the 3rd calibration node and the LDM and the height H₀ and thedistance D₀ between the LDM and the terminal pivot point A comprises useof a following set of equations:

H _(y) =H ₀ +Ĥ _(H), and

H _(x) =D ₀ +{circumflex over (D)} _(H).   (Equations 7-8)

In embodiments, the architecture controller is further programmed toexecute machine readable instructions to determine a total height {hacekover (H)} and a total distance Ď between the terminal point G and theterminal pivot point A based on a boom limb length L_(B), a stick limblength L_(S), a boom angle θ_(B), and a stick angle θ_(S). For example,and referring to FIG. 3, L_(S) is a stick limb length of the excavatorstick 110, θ_(S) is a stick angle of the excavator stick 110 relative togravity, L_(B) is a boom limb length of the excavator boom 108, and 0_(B) is a boom angle of the excavator boom 108 relative to gravity.Further, the architecture controller is programmed to determine a totalheight {hacek over (H)} and a total distance Ď between the terminalpivot point B and the terminal pivot point A based on a boom limb lengthL_(B), and a boom angle θ_(B). The architecture controller is programmedto identify a height H₀ and a distance D₀ between the LDM and theterminal pivot point A.

The iterative process further comprises identifying respective positionsof two other nodes that, together with the nth calibration node, form anexternal triangle. The two other nodes comprise one of nodes D, F, G, H,and a node corresponding to a position of the terminal pivot point B ofthe excavator boom 108. Further, in step 212, the iterative processcomprises determining side lengths for each of the legs of the externaltriangle formed between the nth calibration node and two other nodes. Instep 214, the iterative process comprises determining triangular anglesof the external triangle based on the side lengths of the externaltriangle. In embodiments and referring to FIG. 4, the external trianglesmay comprise triangles BGD, BDF, and GFH.

For example, when n=1 and the 1st calibration node is positioned at thenode D, the two other nodes comprise the terminal pivot point B and thenode G, the legs of the external triangle comprise GD, BD, BG, and thetriangular angles of the external triangle comprise angles BGD, GDB, DBGand are determined based on the side lengths determined for the legs GD,BD, and BG and the law of cosines.

Further, determining the side lengths for the legs BG, GD, and BDcomprises calculating the side length for the leg BG based on the totalheight {hacek over (H)} and the total distance Ď between the node G andthe terminal pivot point A, respectively comprising G_(y) and G_(x) andthe total height {hacek over (H)} and the total distance Ď between theterminal pivot point B and the terminal pivot point A, respectivelycomprising B_(y) and B_(x). With respect to G_(y) and G_(x), a followingset of equations may be used:

G _(y) =L _(S) cos(θ_(S))+L _(B) cos(θ_(B)), and

G _(x) =L _(S) sin(θ_(S))+L _(B) sin(θ_(B)).   (Equations 9-10)

With respect to B_(y) and B_(x), a following set of equations may beused:

B _(y) =L _(B) cos(θ_(B)), and

B _(x) =L _(B) sin(θ_(B)).   (Equations 11-12)

Thus, determining the side lengths for the legs BG, GD, and BD mayinclude a following set of equations:

BG=√{square root over ((G _(y) −B _(y))²+(G _(x) −B _(x))²)},

GD=√{square root over ((G _(y) −D _(y))²+(G _(x) −D _(x))²)}, and

BD=√{square root over ((D _(y) −B _(y))²+(D _(x) −B _(x))²)}  (Equations13-15)

The side length BG should be a length of the excavator stick and shouldbe equivalent to L_(S). In further embodiments, the excavator boomfurther comprises a variable-angle (VA) excavator boom, and for whichL_(V) is a limb length of the VA excavator boom, and θ_(V) is a VA boomangle of the VA excavator boom relative to gravity:

G _(y) =L _(V) cos(θ_(V))+L _(S) cos(θ_(S))+L _(B) cos(θ_(B)), and

G _(x) =L _(V) sin(θ_(V))+L _(S) sin(θ_(S))+L _(B) sin(θ_(B)).  (Equations 16-17)

In such embodiments, with a VA excavator boom, the total height {hacekover (H)} and the total distance Ď between the terminal pivot point Band the terminal pivot point A, respectively comprising By and Bx, suchthat:

B _(y) =L _(V) cos(θ_(V))+L _(B) cos(θ_(B)), and

B _(x) =L _(V) sin(θ_(V))+L _(B) sin(θ_(B)).   (Equations 18-19)

In embodiments, when n=2 and the 2nd calibration node is positioned atthe node F, the two other nodes comprise the terminal pivot point B andthe node D. Further, the legs of the external triangle comprise DF, BF,and BD, where

DF=√{square root over ((D _(y) −F _(y))²+(D _(x) −F _(x))²)}, and

BF=√{square root over ((B _(y) −F _(y))²+(B _(x) −F _(x))²)}.  (Equations 20-21)

Additionally, the triangular angles of the external triangle compriseangles BDF, DFB, FBD and are determined based on the side lengthsdetermined for the legs DF, BF, and BD and the law of cosines. The angleBDF is representative of an actual dogbone angle BDF.

In an embodiment, the excavator further comprises an implement dynamicsensor disposed on a dogbone linkage DF of the four-bar linkage 112. Thearchitecture controller is further programmed to execute machinereadable instructions to generate a dogbone measured angle θ_(DF) fromthe implement dynamic sensor. Further, the machine readable instructionsmay comprise instructions to compare the dogbone measured angle θ_(DF)to an actual dogbone angle BDF to determine a bias therebetween, andcalibrate the implement dynamic sensor based on the bias. One or moredynamic sensors may include the implement sensor and dynamic sensors120, 122 positioned on other excavator limbs such as the excavator boom108 and the excavator stick 110, which are similar to the implementdynamic sensor. The one or more dynamic sensors may comprise an inertialmeasurement unit (IMU), an inclinometer, an accelerometer, a gyroscope,an angular rate sensor, a rotary position sensor, a position sensingcylinder, or combinations thereof. The IMU may comprise a 3-axisaccelerometer and a 3-axis gyroscope. As shown in FIG. 2, the dynamicsensors 120, 122 include accelerations A_(x), A_(y), and A_(z),respectively representing x-axis, y-axis-, and z-axis accelerationvalues.

In embodiments when n=3 and the 3rd calibration node is positioned atthe node H, the two other nodes comprise the node F and the node G.Further, the legs of the external triangle comprise GH, FH, and FG,where

GH=√{square root over ((G _(y) −H _(y))²+(G _(x) −H _(x))²)},

FH=√{square root over ((F _(y) −H _(y))²+(F _(x) −H _(x))²)}, and

FG=√{square root over ((F _(y) −G _(y))²+(F _(x) −G _(x))²)}.  (Equations 22-23)

Additionally, the triangular angles of the external triangle compriseangles FGH, GHF, HFG and are determined based on the side lengthsdetermined for the legs GH, FH, and FG and the law of cosines.

The architecture controller is further programmed to repeat theiterative process n times until triangular angles and side lengths of atleast three external triangles are determined. The external trianglesform an internal triangle therebetween. Further, the internal triangleshares two nodes and one side with each of the three external trianglesand comprises a set of three internal triangle side lengths. In anembodiment and referring to FIG. 4, the internal triangle comprisesinternal triangle GDF disposed between and internally of externaltriangles BGD, BDF, and GFH. The internal triangle GDF shares nodes Gand D with the external triangle BGD, nodes DF with the externaltriangle BDF, and nodes F and G with the external triangle GFH.

As a non-limiting example, in step 216, the iterative process determinesif sufficient distances and angles of three external triangles formingan internal triangle have been determined. If the answer is no, theiterative process proceeds to step 218 and repeat step 204 to positionthe excavating linkage assembly 104 at a next linkage assembly positionn. If the answer is yes, the iterative process proceeds to step 220.

The architecture controller is further programmed to, as shown in step220, determine the angles of the internal triangle at least partiallybased on the set of three internal triangle side lengths. As anon-limiting example, when, as described above, the 1st, 2nd, and 3rdcalibration nodes have been respectively positioned at the nodes D, F,and H through the iterative process, in step 220, the set of internaltriangle side lengths are length are legs DF, FG, and GD that form theinternal triangle. Further, the angles of the internal triangle compriseangles DGF, GDF, and DFG and are determined based on the determined sidelengths of the legs DF, FG, and GD and the law of cosines.

The architecture controller is further programmed to, as shown in step222, generate an implement angle of the excavating implement at leastpartially based on a summation of a set of adjacent determinedtriangular angles. The set of adjacent determined triangular anglescomprises an angle from the internal triangle and angles from at leasttwo of the external triangles. In the example above, generating theimplement angle comprises generate an angle BGH based on a summation ofthe determined angles DGF, BGD, and FGH. The architecture controller isfurther programmed to, as shown in step 224, operate the excavator usingthe implement angle.

It is contemplated that the embodiments of the present disclosure mayassist to permit a speedy and more cost efficient method of determiningimplement dimensions such as an implement angle, and methods todetermine and calibrate sensor offsets of sensors on excavator linkages,in a manner that minimizes a risk of human error with such valuedeterminations. Further, the controller of the excavator or othercontrol technologies are improved such that the processing systems areimproved and optimized with respect to speed, efficiency, and output.

A signal may be “generated” by direct or indirect calculation ormeasurement, with or without the aid of a sensor.

For the purposes of describing and defining the present invention, it isnoted that reference herein to a variable being a “function” of aparameter or another variable is not intended to denote that thevariable is exclusively a function of the listed parameter or variable.Rather, reference herein to a variable that is a “function” of a listedparameter is intended to be open ended such that the variable may be afunction of a single parameter or a plurality of parameters.

It is also noted that recitations herein of “at least one” component,element, etc., should not be used to create an inference that thealternative use of the articles “a” or “an” should be limited to asingle component, element, etc.

It is noted that recitations herein of a component of the presentdisclosure being “configured” or “programmed” in a particular way, toembody a particular property, or to function in a particular manner, arestructural recitations, as opposed to recitations of intended use. Morespecifically, the references herein to the manner in which a componentis “configured” or “programmed” denotes an existing physical conditionof the component and, as such, is to be taken as a definite recitationof the structural characteristics of the component.

It is noted that terms like “preferably,” “commonly,” and “typically,”when utilized herein, are not utilized to limit the scope of the claimedinvention or to imply that certain features are critical, essential, oreven important to the structure or function of the claimed invention.Rather, these terms are merely intended to identify particular aspectsof an embodiment of the present disclosure or to emphasize alternativeor additional features that may or may not be utilized in a particularembodiment of the present disclosure.

For the purposes of describing and defining the present invention it isnoted that the terms “substantially” and “approximately” are utilizedherein to represent the inherent degree of uncertainty that may beattributed to any quantitative comparison, value, measurement, or otherrepresentation. The terms “substantially” and “approximately” are alsoutilized herein to represent the degree by which a quantitativerepresentation may vary from a stated reference without resulting in achange in the basic function of the subject matter at issue.

Having described the subject matter of the present disclosure in detailand by reference to specific embodiments thereof, it is noted that thevarious details disclosed herein should not be taken to imply that thesedetails relate to elements that are essential components of the variousembodiments described herein, even in cases where a particular elementis illustrated in each of the drawings that accompany the presentdescription. Further, it will be apparent that modifications andvariations are possible without departing from the scope of the presentdisclosure, including, but not limited to, embodiments defined in theappended claims. More specifically, although some aspects of the presentdisclosure are identified herein as preferred or particularlyadvantageous, it is contemplated that the present disclosure is notnecessarily limited to these aspects.

It is noted that one or more of the following claims utilize the term“wherein” as a transitional phrase. For the purposes of defining thepresent invention, it is noted that this term is introduced in theclaims as an open-ended transitional phrase that is used to introduce arecitation of a series of characteristics of the structure and should beinterpreted in like manner as the more commonly used open-ended preambleterm “comprising.”

What is claimed is:
 1. An excavator calibration framework comprising anexcavator, a laser distance meter (LDM), and a plurality of laserreflectors, wherein: the excavator comprises a machine chassis, anexcavating linkage assembly, an excavating implement, and controlarchitecture; the excavating linkage assembly comprises an excavatorboom, an excavator stick, the excavating implement, and a four-barlinkage that collectively define a plurality of linkage assemblypositions; the excavator stick comprises a terminal point and ismechanically coupled to a terminal pivot point B of the excavator boom;the four-bar linkage comprises a node D, a node F, a node G, a node H,and linkages disposed therebetween; the node G of the four-bar linkageis disposed at a position corresponding to the terminal point of theexcavator stick through which the excavator stick is coupled to theexcavating implement; the LDM is configured to generate an LDM distancesignal D_(LDM) indicative of a distance between the LDM and the laserreflector and an angle of inclination signal θ_(INC) indicative of anangle between the LDM and the laser reflector; the plurality of laserreflectors are disposed at respective positions corresponding to thenodes D, F, G, and H of the four-bar linkage; the control architecturecomprises one or more linkage assembly actuators and an architecturecontroller programmed to execute an iterative process at n linkageassembly positions, the iterative process comprising: positioning theexcavating linkage assembly at a linkage assembly position n; settingone of the nodes D, F, G, and H as the nth calibration node with theexcavating linkage assembly at the linkage assembly position n,determining a height H and a distance D between the nth calibration nodeand the LDM based on the LDM distance signal D_(LDM) and angle ofinclination signal θ_(INC); and determining a position of the nthcalibration node at least partially based on the height Ĥ and thedistance {circumflex over (D)}; identifying respective positions of twoother nodes that, together with the nth calibration node, form anexternal triangle, the two other nodes comprising one of nodes D, F, G,H, and a node corresponding to a position of the terminal pivot point Bof the excavator boom; determining side lengths for each of the legs ofthe external triangle formed between the nth calibration node and twoother nodes; and determining triangular angles of the external trianglebased on the side lengths of the external triangle; and the architecturecontroller is further programmed to: repeat the iterative process ntimes until triangular angles and side lengths of at least threeexternal triangles are determined, wherein the external triangles forman internal triangle therebetween, the internal triangle shares twonodes and one side with each of the three external triangles andcomprises a set of three internal triangle side lengths; determine theangles of the internal triangle at least partially based on the set ofthree internal triangle side lengths; generate an implement angle of theexcavating implement at least partially based on a summation of a set ofadjacent determined triangular angles, the set of adjacent determinedtriangular angles comprising an angle from the internal triangle andangles from at least two of the external triangles; and operate theexcavator using the implement angle.
 2. An excavator calibrationframework as claimed in claim 1, wherein the linkages comprise animplement linkage GH, a rear side linkage FH, a dogbone linkage DF, anda front side linkage GD.
 3. An excavator calibration framework asclaimed in claim 1, wherein: the machine chassis is mechanically coupledto a terminal pivot point A of the excavator boom; and in the iterativeprocess, determining a position of the nth calibration node at leastpartially based on the height Ĥ and the distance {circumflex over (D)}comprises: calculating a total height {hacek over (H)} and a totaldistance Ď between the nth calibration node and the terminal pivot pointA of the excavator boom based on a summation of the height Ĥ and thedistance {circumflex over (D)} between the nth calibration node and theLDM and the height H₀ and the distance D₀ between the LDM and theterminal pivot point A.
 4. An excavator calibration framework as claimedin claim 1, wherein the architecture controller is further programmed toexecute machine readable instructions to determine a total height {hacekover (H)} and a total distance Ď between the terminal point G and theterminal pivot point A based on a boom limb length L_(B), a stick limblength L_(S), a boom angle θ_(B), and a stick angle θ_(S), determine atotal height {hacek over (H)} and a total distance Ď between theterminal pivot point B and the terminal pivot point A based on a boomlimb length L_(B), and a boom angle θ_(B), and identify a height H₀ anda distance D₀ between the LDM and the terminal pivot point A.
 5. Anexcavator calibration framework as claimed in claim 1, wherein: for n=1,the 1st calibration node is positioned at the node D; for n=2, the 2ndcalibration node is positioned at the node F; and for n=3, the 3rdcalibration node is positioned at the node H.
 6. An excavatorcalibration framework as claimed in claim 1, wherein: the machinechassis is mechanically coupled to a terminal pivot point A of theexcavator boom; and when n=1: the 1st calibration node is positioned atthe node D, such that calculating a total height {hacek over (H)} and atotal distance Ď between the 1st calibration node and the terminal pivotpoint A of the excavator boom, respectively comprising D_(y) and D_(x),is based on a summation of the height Ĥ and the distance {circumflexover (D)} between the 1st calibration node and the LDM and the height H₀and the distance D₀ between the LDM and the terminal pivot point A; thetwo other nodes comprise the terminal pivot point B and the node G; thelegs of the external triangle comprise GD, BD, BG; and the triangularangles of the external triangle comprise angles BGD, GDB, DBG and aredetermined based on the side lengths determined for the legs GD, BD, andBG and the law of cosines.
 7. An excavator calibration framework asclaimed in claim 6, wherein determining the side lengths for the legsBG, GD, and BD comprises calculating the side length for the leg BGbased on: the total height {hacek over (H)} and the total distance Ďbetween the node G and the terminal pivot point A, respectivelycomprising G_(y) and G_(x); and the total height Ĥ and the totaldistance {circumflex over (D)} between the terminal pivot point B andthe terminal pivot point A, respectively comprising B_(y) and B_(x). 8.An excavator calibration framework as claimed in claim 7, wherein whenn=2: the 2nd calibration node is positioned at pin F, such thatcalculating a total height Ĥ and a total distance {circumflex over (D)}between the 2nd calibration node and the terminal pivot point A of theexcavator boom, respectively comprising F_(y) and F_(x), is based on asummation of the height Ĥ and the distance {circumflex over (D)} betweenthe 2nd calibration node and the LDM and the height H₀ and the distanceD₀ between the LDM and the terminal pivot point A; the two other nodescomprise the terminal pivot point B and the node D; the legs of theexternal triangle comprise DF, BF, and BD; the triangular angles of theexternal triangle comprise angles BDF, DFB, FBD and are determined basedon the side lengths determined for the legs DF, BF, and BD and the lawof cosines; and the angle BDF is representative of an actual dogboneangle BDF.
 9. An excavator calibration framework as claimed in claim 8,wherein when n=3: the 3rd calibration node is positioned at pin H, suchthat calculating a total height {hacek over (H)} and a total distance Ďbetween the 3rd calibration node and the terminal pivot point A of theexcavator boom, respectively comprising H_(y) and H_(x), based on asummation of the height Ĥ and the distance {circumflex over (D)} betweenthe 3rd calibration node and the LDM and the height H₀ and the distanceD₀ between the LDM and the terminal pivot point A; the two other nodescomprise the node F and the node G; the legs of the external trianglecomprise GH, FH, and FG; and the triangular angles of the externaltriangle comprise angles FGH, GHF, HFG and are determined based on theside lengths determined for the legs GH, FH, and FG and the law ofcosines.
 10. An excavator calibration framework as claimed in claim 9,wherein: the set of internal triangle side lengths are length are legsDF, FG, and GD that form the internal triangle; the angles of theinternal triangle comprise angles DGF, GDF, and DFG and are determinedbased on the determined side lengths of the legs DF, FG, and GD and thelaw of cosines; and generating the implement angle comprises generate anangle BGH based on a summation of the determined angles DGF, BGD, andFGH.
 11. An excavator calibration framework comprising an excavator, alaser distance meter (LDM), and a plurality of laser reflectors,wherein: the excavator comprises a machine chassis, an excavatinglinkage assembly, an excavating implement, and control architecture; theexcavating linkage assembly comprises an excavator boom, an excavatorstick, the excavating implement, and a four-bar linkage thatcollectively define a plurality of linkage assembly positions; the LDMis configured to generate an LDM distance signal D_(LDM) indicative of adistance between the LDM and the laser reflector and an angle ofinclination signal θ_(INC) indicative of an angle between the LDM andthe laser reflector; the plurality of laser reflectors are disposed atrespective positions corresponding to a plurality of nodes of thefour-bar linkage; the control architecture comprises one or more linkageassembly actuators and an architecture controller programmed to executean iterative process at n linkage assembly positions to determine aposition of an nth calibration node of the plurality of nodes of thefour-bar linkage to determine triangular angles and side lengths of anexternal triangle formed between the nth calibration node and two othernodes having identified positions; repeat the iterative process n timesuntil triangular angles and side lengths of at least three externaltriangles are determined, wherein the external triangles form aninternal triangle therebetween, the internal triangle shares two nodesand one side with each of the three external triangles and comprises aset of three internal triangle side lengths; determine the angles of theinternal triangle at least partially based on the set of three internaltriangle side lengths; generate an implement angle of the excavatingimplement at least partially based on a summation of a set of adjacentdetermined triangular angles, the set of adjacent determined triangularangles comprising an angle from the internal triangle and angles from atleast two of the external triangles; and operate the excavator using theimplement angle.
 12. An excavator calibration framework as claimed inclaim 11, wherein the excavating implement and the excavator stick aremechanically coupled to each other through the four-bar linkage.
 13. Anexcavator calibration framework as claimed in claim 11, wherein theexcavator stick comprises a terminal point and is mechanically coupledto a terminal pivot point B of the excavator boom.
 14. An excavatorcalibration framework as claimed in claim 11, wherein the plurality ofnodes of the four-bar linkage comprise a node D, a node F, a node G, anode H, and linkages disposed therebetween.
 15. An excavator calibrationframework as claimed in claim 14, wherein the node G of the four-barlinkage is disposed at a position corresponding to the terminal point ofthe excavator stick through which the excavator stick is coupled to theexcavating implement.
 16. An excavator calibration framework as claimedin claim 11, wherein the iterative process comprises: positioning theexcavating linkage assembly at a linkage assembly position n; settingone of the nodes D, F, G, and H as the nth calibration node with theexcavating linkage assembly at the linkage assembly position n,determining a height Ĥ and a distance {circumflex over (D)} between thenth calibration node and the LDM based on the LDM distance signalD_(LDM) and angle of inclination signal θ_(INC); and determining aposition of the nth calibration node at least partially based on theheight Ĥ and the distance {circumflex over (D)}; identifying respectivepositions of two other nodes that, together with the nth calibrationnode, form the external triangle, the two other nodes comprising one ofnodes D, F, G, H, and a node corresponding to a position of the terminalpivot point B of the excavator boom; determining side lengths for eachof three legs of the external triangle formed between the nthcalibration node and two other nodes; and determining triangular anglesof the external triangle based on the side lengths of the externaltriangle.
 17. An excavator calibration framework as claimed in claim 16,wherein: for n=1, the 1st calibration node is positioned at the node D;for n=2, the 2nd calibration node is positioned at the node F; and forn=3, the 3rd calibration node is positioned at the node H.
 18. Anexcavator calibration framework as claimed in claim 11, wherein thecontrol architecture comprises a non-transitory computer-readablestorage medium comprising machine readable instructions.
 19. Anexcavator calibration framework as claimed in claim 11, wherein the oneor more linkage assembly actuators facilitate movement of the excavatinglinkage assembly.
 20. An excavator calibration framework as claimed inclaim 19, wherein the one or more linkage assembly actuators comprise ahydraulic cylinder actuator, a pneumatic cylinder actuator, anelectrical actuator, a mechanical actuator, or combinations thereof.